OLMo 2 is a family of fully-open language models designed for accessibility and reproducibility in AI research. The largest model, OLMo 2 32B, surpasses GPT-3.5-Turbo and GPT-4o mini on various academic benchmarks, while the smaller models (7B, 13B, and 1B) are competitive with other open-weight models. Ai2 emphasizes the importance of open training data and code to advance collective scientific research.